New research suggests that the seemingly useless organ provides a safe haven for good bacteria to hang out in the gut.

Although the study stops short of providing direct proof of this proposed purpose for the appendix, researchers say there's a strong case to be made for the appendix based on new information about the role of bacteria in intestinal health.

"While there is no smoking gun, the abundance of circumstantial evidence makes a strong case for the role of the appendix as a place where the good bacteria can live safe and undisturbed until they are needed," researcher William Parker, PhD, assistant professor of experimental surgery at Duke University Medical Center, says in a news release.

The appendix is a small, 2- to 4-inch pouch located near where the large and small intestines meet. Doctors have debated the exact function of the organ for years, as removal causes no noticeable symptoms.

Not much is known about the human appendix because studies on the appendix are difficult to conduct. There are only a few animals that have the organ; an animal's appendix is very different than the human appendix.

A Higher Purpose for the Appendix

Researchers deduce that the appendix is designed to protect good bacteria in the gut.

That way, when the gut is affected by a bout of diarrhea or other illness that cleans out the intestines, the good bacteria in the appendix can repopulate the digestive system and keep you healthy.

But in a modern society less of these good bacteria are needed due to better hygiene practices, which may explain why the appendix has gained a reputation as a useless organ.

"Once the bowel contents have left the body, the good bacteria hidden away in the appendix can emerge and repopulate the lining of the intestine before more harmful bacteria can take up residence," says Parker. "In industrialized societies with modern medical care and sanitation practices, the maintenance of a reserve of beneficial bacteria may not be necessary. This is consistent with the observation that removing the appendix in modern societies has no discernable negative effects."

In addition, according to the hygiene hypothesis, the lack of germs in modern society may cause the immune system to overreact and attack the good bacteria stored away in the appendix.

"This over-reactive immune system may lead to the inflammation associated with appendicitis and could lead to the obstruction of the intestines that causes acute appendicitis," Parker says. "Thus, our modern health care and sanitation practices may account not only for the lack of a need for an appendix in our society, but also for much of the problems caused by the appendix in our society."